Shear foil and method of making the same

Abstract

A shear foil and method of making the same includes providing a surface of a matrix element with a grid of depressions, and overfilling the depressions with a metallic molding substance so as to form a plurality of metallic inserts each of which overlaps a narrow annular region of the surface which bounds a respective depression filled by the respective insert. A layer of metallic screen-forming substance is thereupon deposited over the metallic inserts so as to form a screen having a plurality of openings which extend to the surface intermediate respectively adjacent inserts. The screen also has a face comprised of annular face portions each of which surrounds one of the inserts and which is juxtaposed with the surface of the matrix element. The deposition of a layer of sealing material over the surface of said screen which faces away from said surface of said matrix element, follows. The matrix element is thereupon separated from the screen and the inserts so as to expose the latter and said face. A layer of wear-resistant substance, such as chromium, is then deposited over the exposed face and inserts. The portion of the wear-resistant layer which is deposited on the inserts and thereupon removed from the screen while the remaining portion of the wear-resistant layer on the annular face portions by separating the inserts from the screen. An additional layer of hydrogen-impermeable substance may also be deposited intermediate the matrix element and the screen.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims. 
     
       1. A method of making a shear foil, comprising the steps of providing a matrix element with a plurality of isles which are separated by a shallow grid-spaced recess and which have a matrix surface; overfilling said recess with a molding substance and forming a plurality of inserts each of which overlaps a narrow annular region of said matrix surface; depositing a layer of screen-forming substance over said inserts and forming a screen having a plurality of openings which extend to said matrix surface intermediate respectively adjacent inserts, said screen also having a face comprised of annular face portions each of which surrounds one of said inserts and is juxtaposed with said matrix surface; separating said matrix element and the isles from said screen and said insert and exposing said inserts and said face; depositing a layer of wear-resistant substance over said exposed face and inserts; and removing the portion of said wear-resistant layer deposited on said inserts, while leaving the remaining portion of said wear-resistant layer on said annular face portions, by separating said inserts from said screen. 
     
     
       2. A method as defined in claim 1, wherein said step of overfilling said recess with a molding substance, said step of depositing a layer of screen-forming substance, and said step of depositing a layer of wear-resistant substance all comprise the step of electro-depositing the respective substance. 
     
     
       3. The method as defined in claim 1, wherein said step of overfilling said recess with a molding substance comprises electro-depositing nickel into said recess. 
     
     
       4. A method as defined in claim 1, wherein said step of depositing a layer of wear-resistant substance comprises electro-depositing chrome over said exposed face and inserts. 
     
     
       5. A method as defined in claim 4, wherein said step of electro-depositing chrome includes building up the latter to a thickness ranging from at least 1 to at most 5 micrometers. 
     
     
       6. A method as defined in claim 1; and further comprising the step of depositing a layer of sealing material over the surface of said screen which faces away from said matrix surface of said isles, prior to the separating step. 
     
     
       7. A method as defined in claim 1; and further comprising the step of depositing a layer of hydrogen-impermeable substance intermediate said matrix element and said screen. 
     
     
       8. A method as defined in claim 7, wherein said step of depositing a layer of hydrogen-impermeable substance comprises electro-depositing the latter intermediate said inserts and said screen. 
     
     
       9. A method as defined in claim 7, wherein said step of depositing a layer of hydrogen-impermeable substance comprises electro-depositing the latter intermediate said inserts and said matrix element. 
     
     
       10. A method as defined in claim 7, wherein said step of depositing a layer of hydrogen-impermeable substance is performed simultaneously with said step of overfilling said depressions. 
     
     
       11. A shear foil, particularly for use in electric shavers, comprising a screen having a plurality of screen elements wjhich bound a plurality of screen openings, each screen element having an annular projection and an annular face portion at a free end of the respective annular projection; and a layer of metallic wear-resistant material overlying all of said annular face portions of said screen, said layer having a lip surrounding a marginal edge portion of each annular projection adjacent each annular face portion. 
     
     
       12. A shear foil as defined in claim 11, wherein said layer of metallic wear-resistant material constitutes chrome electro-deposited at said annular face portions to have a thickness of at least 1 and at most 5 micrometers. 
     
     
       13. A shear foil as defined in claim 11, wherein each lip of metallic wear-resistant material extends at least in part into opening.